Biomedical subjects

Y Kanagasingam

Publications and source records attributed to Y Kanagasingam.

7 recordsLinked to original sources

PubMed2001

Working toward a portable tele-ophthalmic system for use in maximum-security prisons: a pilot study.

The medical care of prisoners is a difficult and often costly process. Basic medical needs are serviced by prison medical officers. However, specialized care often means transport to specialist centers with the attendant cost and safety. We examined portable ophthalmic equipment in a prison environment to screen 11 prisoners who were scheduled for specialist ophthalmic assessment. Medical and ophthalmic histories were documented, visual acuity was tested, digital images were taken of the external eye and retina, and intraocular pressures taken. The data were sent via modem to a specialist ophthalmologist, and the reports were dictated via e-mail at the end of each session. Of the 11 patients who were scheduled to travel for ophthalmic assessment, only 2 were still required to travel to a specialist ophthalmic center. This pilot study showed that there were considerable cost savings to be made by this screening process with the attendant increase in community safety. The prototype equipment requires refinement by further experimentation, but showed the potential as an adjunct to current examination and assessment techniques when applied to a prison population.

Adult↗

PubMed2000

Long-term real-time monitoring of adeno-associated virus-mediated gene expression in the rat retina.

PURPOSE: Previous studies have demonstrated that adeno-associated virus (AAV) efficiently transduced retinal pigmented epithelial (RPE) cells. The goal of this study was to further evaluate and characterize transgene expression within the RPE cells over time in vivo. METHODS: Adeno-associated virus-mediated gene transfer was monitored and quantified by retinal photography following subretinal injection of a recombinant AAV encoding the green fluorescent protein gene (rAAVCMV-gfp) into rat eyes. Retinal function of transduced rat eyes was measured by electroretinography. RESULTS: The maximum level of transgene expression was reached at 8 weeks postinjection followed by a gradual decrease throughout the experimental period. Interestingly, it was observed that while gfp expression was stable in some RPE cells, gfp fluorescence completely disappeared in other cells over the duration of the experiment. The expression of AAV-mediated gfp in RPE cells did not alter the retinal function for over 1 year CONCLUSIONS: These results confirm the importance of this direct visualization system to study vector transgene expression in vivo and support the use of AAV for diseases treatable by targeting RPE cells.

Animals↗

PubMed2000

Computer-assisted planimetry associated with Sturge-Weber syndrome.

Photographs of the optic nerve head (optic disc) in the eye are used for the clinical assessment of the disease glaucoma. These images are usually subjectively assessed by a clinician. A case of Sturge-Weber Syndrome which includes glaucoma as a symptom, is presented here. Narrowing of the rim of the optic disc was measured using custom-made measurement software confirming glaucomatous progression. To maximize the information obtained from optic disc images, low cost software can assist with quantifying disc parameters aiding clinical interpretation.

Adolescent↗

PubMed2000

Comparison of optic disc image assessment methods when examining serial photographs for glaucomatous progression.

AIM: To assess serial, simultaneous stereo optic disc images by four methods for glaucomatous progression. METHODS: Using varying techniques, two ophthalmologists assessed serial optic disc images of 52 eyes from 27 patients with a mean duration between images of 18 months. The neuroretinal rim width was qualitatively assessed by four assessment methods and compared with quantitative rim measurements made using PC based software. RESULTS: The highest sensitivity of 83% was achieved using computerised stereo chronoscopy. CONCLUSION: Stereo chronoscopy improved the detection of subtle optic disc changes when compared with simpler assessment techniques.

Disease Progression↗

PubMed1999

Evaluation of adeno-associated virus-mediated gene transfer into the rat retina by clinical fluorescence photography.

The purpose of this study was to evaluate recombinant adeno-associated virus (AAV) as an in vivo gene transfer vector for the retina and to explore the possibility of monitoring the expression of green fluorescent protein (GFP) using a noninvasive method. Rats were injected subretinally with rAAV-gfp or rAAV-lacZ. Strong expression of the reporter gene in a circular area surrounding the injection site was observed in retinal whole mounts and tissue sections. Higher magnification revealed that cells demonstrating high levels of green fluorescence were hexagonal in shape, indicating they were retinal pigment epithelium (RPE) cells. Histological observation of retinal sections demonstrated that recombinant AAV specifically transduced RPE cells. Ten animals were injected with rAAV-gfp for longitudinal studies and the fluorescence was monitored by retinal fluorescence photography. The GFP signal was detected in 100% of the animals as early as 2 weeks postinjection and remained present throughout the experimental period of 4 months. After 2 weeks, a gradual increase in the number of transduced cells occurred before reaching maximal levels of GFP expression at 8 weeks. This was followed by a small decrease over 4 weeks before reaching stable expression at 16 weeks. Our results demonstrated that rAAV efficiently transduces rat RPE cells and that retinal fluorescence photography is suitable for monitoring GFP expression. By using this noninvasive technique, we demonstrated that repetitive measurements of GFP expression in vivo in the rAAV-gfp-transduced retina are possible. This study demonstrated that retinal fluorescence photography is a potent tool for studying AAV-mediated gene delivery in the retina.

Animals↗

PubMed1999

Optic disc topographic changes post-trabeculectomy visualized by anaglyphs.

BACKGROUND: Publications on changes of optic disc topography usually illustrate their findings with two-dimensional images. METHODS: With the introduction of computerized imaging, anaglyphs of stereo images can be produced for illustrations. Anaglyphs are viewed three-dimensionally with red-green spectacles that are included in refraction sets and are normally used to assess phoria. An anaglyph of progressive, glaucomatous progression is included to demonstrate the method, along with conventional colour images. RESULTS: We present two cases of severely altered optic disc topography post-trabeculectomy and illustrate these cases with anaglyphs that can be viewed three-dimensionally. CONCLUSION: Three-dimensional viewing of illustrations assists with the visualization, perception and interpretation of optic disc changes.

Aged↗

PubMed1997

Prognostic factors in patients with metastatic (stage D2) prostate cancer: experience from the Scandinavian Prostatic Cancer Group Study-2.

PURPOSE: Nuclear texture reflects the overall structures of the chromatin organization. We recently reported the principles and prognostic importance of image analysis of nuclei from metastatic prostate cancer. Immunohistochemical up regulation of the adhesion molecule sialyl Lewis(x) is also reported to be a prognostic parameter. Presently we analyzed statistically the prognostic impact of these 2 new parameters compared to well-known clinical parameters in metastatic prostate cancer. MATERIALS AND METHODS: Prognostic factors, such as sedimentation rate, alkaline and acid phosphatases, hemoglobin, testosterone, performance status, pain due to metastasis, T category, histological grade and patient age, were included in a multivariate Cox proportional hazards regression analysis based on 262 patients from the Scandinavian Prostatic Cancer Group Study-2. Extent of bone lesions, deoxyribonucleic acid ploidy, texture analysis and sialyl Lewis(x) molecules based on subsets of these 262 patients were also analyzed in the same multivariate model. RESULTS: This test identified chromatin texture as the most important factor (p < 0.001), followed by reaction of the oligosaccharide sialyl Lewis(x) (p < 0.01). Among the routine clinical and laboratory data, sedimentation rate, alkaline phosphatase and hemoglobin (p < 0.05) showed prognostic importance. Performance status, pain due to metastasis and extent of bone lesions showed prognostic value in the univariate analysis (p < 0.05). CONCLUSIONS: These data indicate that computerized nuclear texture analysis as well as up regulation of sialyl Lewis(x) molecules may be new important prognostic factors in metastatic prostate cancer. Furthermore the prognostic importance of sedimentation rate, alkaline phosphatase and hemoglobin was confirmed.

Aged↗